We plan to complete purification of the rat serum vitamin D-binding protein (DBP), and develop assay(s) for its reliable quantitation. We plan to explore the distribution and metabolic clearance of DBP. We seek to apply vitamin D metabolite assay methodology to a variety of clinical disorders. Specifically, we plan to examine the bioavailability of parenterally administered vitamin D. Finally, we shall explore the possibilities of High Pressure Liquid Chromatography (HPLC) and Gas Liquid Chromatorgaphy-Electron Capture Detector (GLC-ECD) in facilitating the quantitation of vitamin D metabolites. BIBLIOGRAPHIC REFERENCES: Rojanasathit, S. and Haddad, J.G., Ontogeny and Effect of Vitamin D Deprivation on Rat Serum 25-hydroxyvitamin D Binding Protein. Endocrinology 100: 642, 1977. Teitelbaum, S., Halverson, J.G., Bates, M., Wise, L. and Haddad, J.C. Abnormalities of Circulating 25-hydroxyvitamin D after Jejunal-ileal Bypass for Obesity. Evidence of an Adaptive Response. Annals of Int. Med. 86:289, 1977.